Iraqi police have now arrested 19 men as suspects in the Najaf bombing. The Saudi government is worried that the investigation in Iraq will reveal that Saudi Islamic radicals are heavily involved in the Iraqi terrorism. This is political dynamite. Al Qaeda has always had as its core members Sunni Arabs who have a long history of anti-Shia prejudice. If these attitudes can be traced to the Najaf bombing, it will be a major diplomatic problem for Saudi Arabia for some time.